The methylgalactoside permease (MeGa1P) is a multicomponent transport system of Escherichia coli K-12 which mediates the intracellular accumulation of D-galactose and closely related sugars. The genetic locus of MeGa1P has been located at 45 min on the chromosome and shown to consist of four closely linked genes, mg1A, B, C, and D. At present, only the product of one of the genes, mg1B, has been isolated. It has been characterized as a galactose-binding protein. Thus, the next logical step towards the objective of understanding transport mechanisms is to identify the products of mg1A and mg1C genes (since mg1D is a regulator gene, studies of mg1D are not included here). Recent developements from this laboratory have provided means to detect in vivo activity of the mg1A and C genes in the absence of a functional galactose-binding protein. The overall objectives of this project are: a) Isolation of chromosomal DNA segments containing individual mg1 genes; b) molecular cloning of each DNA-mg1 segment using plasmid pBR322 as the vehicle; c) identification of mg1 gene products using bacterial minicells harboring pBR322-mg1 recombinant plasmids; d) purification and functional characterization of each of the mg1 gene products; e) production of antibody specific for mg1 gene products; f) use of the antibodies for physiological and biochemical studies of the MeGa1 transport system.